SHUTOFF GP-AIR 3843663 - Caterpillar

J2 connector, measure the voltage of the first circuit with the wires disconnected. Insert the negative multimeter probe through the vacant hole in the connector body in order to contact with the ECM connector pin at contact J2-25. Use the positive multimeter probe to contact with either the cabinet ground block that is located below the terminal blocks or with a TB2 shield terminal F1.
Measure the voltage of the second circuit with the wires disconnected. Insert the negative multimeter probe through the vacant hole in the connector body in order to contact with the ECM connector pin at the positive contact J2-41. Use the positive multimeter probe to contact with either the cabinet ground block that is located below the terminal blocks or with a TB2 shield terminal M1. Expected Result:Each of the voltage measurements is in the range of negative (-) 15.0 1.5 VDC.Results:
OK - The voltage measurement is in the range of negative (-) 15.0 1.5 VDC. The voltage is correct. The ECM power supply is not causing the problem. Install the wires and sockets that were removed from the J2 connector back into the original locations. Ensure that the sockets are locked in place in the connector body. Proceed to Test Step 3.
NOT OK - Either one or both of the voltage measurements is more negative than negative (-) 16.5 VDC. The ECM power supply is not correct.Repair: Repeat these voltage measurements. Verify that a good cabinet ground point is used for the measurement.If the same voltage measurement is observed, proceed to Test Step 5 in order to check the operation of the ECM.Test Step 3. PERFORM THE POWER ELECTRICAL SYSTEM SERVICE SHUTDOWN PROCEDUREThe next test step will require entry into the Inverter high voltage compartments that contain the system components that are powered by the ECM power supply.When a compartment that contains high voltage components must be entered, the Power Electrical System Service Shutdown procedure must be performed before the cover for the compartment is removed.Reference: Refer to the Troubleshooting, "Electrical Shutdown and Voltage Discharge" section of this manual. Perform the "Power Electrical System Service Shutdown" procedure in order to verify that the voltage in the drive system has been discharged. Once the voltage of the DC bus in the Inverter Dynamic Retarding Contactor compartment is verified as discharged, and a jumper wire is in place, return to this point in this procedure and proceed.Results:
OK - The Power Electrical System Service Shutdown procedure has been performed, the voltage is verified as discharged. The jumper wire is in place. Proceed to the next test step.Test Step 4. CHECK THE COMPONENTS THAT ARE CONNECTED TO THE POWER SUPPLYThe battery disconnect switch and the key start switch remain in the OFF position.The covers for the Inverter low voltage compartments are removed.
At the Inverter Cabinet, remove the high voltage compartment covers that are called out in illustration 2.
Use the high voltage meter to measure for any voltage between the high voltage bus connections in each